Error when make yarn start on /server

[DobleV55]

Error when make $ yarn start
on /fullstack-graphql-airbnb-clone/packages/server

yarn run v1.19.1
warning package.json: No license field
$ cross-env NODE_ENV=development nodemon --exec ts-node src/index.ts
[nodemon] 1.17.5
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: *.*
[nodemon] starting `ts-node src/index.ts`
query: START TRANSACTION
query: SELECT * FROM current_schema()
query: SELECT * FROM "information_schema"."tables" WHERE ("table_schema" = 'public' AND "table_name" = 'listings') OR ("table_schema" = 'public' AND "table_name" = 'users') OR ("table_schema" = 'public' AND "table_name" = 'messages')
query: SELECT *, "udt_name"::"regtype" AS "regtype" FROM "information_schema"."columns" WHERE ("table_schema" = 'public' AND "table_name" = 'listings') OR ("table_schema" = 'public' AND "table_name" = 'users') OR ("table_schema" = 'public' AND "table_name" = 'messages')
query: SELECT "ns"."nspname" AS "table_schema", "t"."relname" AS "table_name", "cnst"."conname" AS "constraint_name", "cnst"."consrc" AS "expression", CASE "cnst"."contype" WHEN 'p' THEN 'PRIMARY' WHEN 'u' THEN 'UNIQUE' WHEN 'c' THEN 'CHECK' END AS "constraint_type", "a"."attname" AS "column_name" FROM "pg_constraint" "cnst" INNER JOIN "pg_class" "t" ON "t"."oid" = "cnst"."conrelid" INNER JOIN "pg_namespace" "ns" ON "ns"."oid" = "cnst"."connamespace" INNER JOIN "pg_attribute" "a" ON "a"."attrelid" = "cnst"."conrelid" AND "a"."attnum" = ANY ("cnst"."conkey") WHERE "t"."relkind" = 'r' AND (("ns"."nspname" = 'public' AND "t"."relname" = 'listings') OR ("ns"."nspname" = 'public' AND "t"."relname" = 'users') OR ("ns"."nspname" = 'public' AND "t"."relname" = 'messages'))
query: SELECT "ns"."nspname" AS "table_schema", "t"."relname" AS "table_name", "i"."relname" AS "constraint_name", "a"."attname" AS "column_name", CASE "ix"."indisunique" WHEN 't' THEN 'TRUE' ELSE'FALSE' END AS "is_unique", pg_get_expr("ix"."indpred", "ix"."indrelid") AS "condition" FROM "pg_class" "t" INNER JOIN "pg_index" "ix" ON "ix"."indrelid" = "t"."oid" INNER JOIN "pg_attribute" "a" ON "a"."attrelid" = "t"."oid"  AND "a"."attnum" = ANY ("ix"."indkey") INNER JOIN "pg_namespace" "ns" ON "ns"."oid" = "t"."relnamespace" INNER JOIN "pg_class" "i" ON "i"."oid" = "ix"."indexrelid" LEFT JOIN "pg_constraint" "cnst" ON "cnst"."conname" = "i"."relname" WHERE "t"."relkind" = 'r' AND "cnst"."contype" IS NULL AND (("ns"."nspname" = 'public' AND "t"."relname" = 'listings') OR ("ns"."nspname" = 'public' AND "t"."relname" = 'users') OR ("ns"."nspname" = 'public' AND "t"."relname" = 'messages'))
query: SELECT "con"."conname" AS "constraint_name", "con"."nspname" AS "table_schema", "con"."relname" AS "table_name", "att2"."attname" AS "column_name", "ns"."nspname" AS "referenced_table_schema", "cl"."relname" AS "referenced_table_name", "att"."attname" AS "referenced_column_name", "con"."confdeltype" AS "on_delete", "con"."confupdtype" AS "on_update" FROM ( SELECT UNNEST ("con1"."conkey") AS "parent", UNNEST ("con1"."confkey") AS "child", "con1"."confrelid", "con1"."conrelid", "con1"."conname", "con1"."contype", "ns"."nspname", "cl"."relname", CASE "con1"."confdeltype" WHEN 'a' THEN 'NO ACTION' WHEN 'r' THEN 'RESTRICT' WHEN 'c' THEN 'CASCADE' WHEN 'n' THEN 'SET NULL' WHEN 'd' THEN 'SET DEFAULT' END as "confdeltype", CASE "con1"."confupdtype" WHEN 'a' THEN 'NO ACTION' WHEN 'r' THEN 'RESTRICT' WHEN 'c' THEN 'CASCADE' WHEN 'n' THEN 'SET NULL' WHEN 'd' THEN 'SET DEFAULT' END as "confupdtype" FROM "pg_class" "cl" INNER JOIN "pg_namespace" "ns" ON "cl"."relnamespace" = "ns"."oid" INNER JOIN "pg_constraint" "con1" ON "con1"."conrelid" = "cl"."oid" WHERE "con1"."contype" = 'f' AND (("ns"."nspname" = 'public' AND "cl"."relname" = 'listings') OR ("ns"."nspname" = 'public' AND "cl"."relname" = 'users') OR ("ns"."nspname" = 'public' AND "cl"."relname" = 'messages')) ) "con" INNER JOIN "pg_attribute" "att" ON "att"."attrelid" = "con"."confrelid" AND "att"."attnum" = "con"."child" INNER JOIN "pg_class" "cl" ON "cl"."oid" = "con"."confrelid" INNER JOIN "pg_namespace" "ns" ON "cl"."relnamespace" = "ns"."oid" INNER JOIN "pg_attribute" "att2" ON "att2"."attrelid" = "con"."conrelid" AND "att2"."attnum" = "con"."parent"
query: COMMIT
query: SELECT "Listing"."id" AS "Listing_id", "Listing"."name" AS "Listing_name", "Listing"."category" AS "Listing_category", "Listing"."pictureUrl" AS "Listing_pictureUrl", "Listing"."description" AS "Listing_description", "Listing"."price" AS "Listing_price", "Listing"."beds" AS "Listing_beds", "Listing"."guests" AS "Listing_guests", "Listing"."latitude" AS "Listing_latitude", "Listing"."longitude" AS "Listing_longitude", "Listing"."amenities" AS "Listing_amenities", "Listing"."userId" AS "Listing_userId" FROM "listings" "Listing"
Error: listen EADDRINUSE :::4000
    at Object._errnoException (util.js:1022:11)
    at _exceptionWithHostPort (util.js:1044:20)
    at Server.setupListenHandle [as _listen2] (net.js:1367:14)
    at listenInCluster (net.js:1408:12)
    at Server.listen (net.js:1492:7)
    at /home/hax0r/Desktop/fullstack-graphql-airbnb-clone/node_modules/graphql-yoga/src/index.ts:368:22
    at new Promise (<anonymous>)
    at GraphQLServer.start (/home/hax0r/Desktop/fullstack-graphql-airbnb-clone/node_modules/graphql-yoga/src/index.ts:366:12)
    at Object.<anonymous> (/home/hax0r/Desktop/fullstack-graphql-airbnb-clone/packages/server/src/startServer.ts:116:28)
    at Generator.next (<anonymous>)
    at fulfilled (/home/hax0r/Desktop/fullstack-graphql-airbnb-clone/packages/server/src/startServer.ts:4:58)
    at <anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:228:7)
[nodemon] app crashed - waiting for file changes before starting...

[benawad]

That error usually comes up if you already have something running on port 4000